code: def test_model_packager_unpack(self) -> None:
      buf = io.BytesIO()
      TestPredictFactoryPackager.save_predict_factory(
          predict_factory=TestPredictFactory,
          configs={"model_name": "sparsenn"},
          output=buf,
          extra_files={
              "dummy_text_field": "test",
              "dummy_binary_field": b"abc",
          },
      )
  
      buf.seek(0)
  
      pi = PackageImporter(buf)
      dummy_text_value = pi.load_text("extra_files", "dummy_text_field")
      self.assertEqual("test", dummy_text_value)
      dummy_binary_value = pi.load_binary(
          "extra_files", "dummy_binary_field"
      )
      self.assertEqual(b"abc", dummy_binary_value)
  
file_path: torchrec/torchrec/inference/tests/model_packager_tests.py
imports: import io
  import tempfile
  import unittest
  import torch.nn
  from torch.package import PackageExporter, PackageImporter
  from torchrec.inference.model_packager import PredictFactoryPackager
  from torchrec.inference.modules import PredictFactory
label_desc: Use image node_id 2 for calling the ModelPackagerTest obj's underlying member method code with example usage: obj.test_model_packager_unpack() without return types